128 SHIPPING PRACTICE The golden rule of agency may be expressed as: " Never exceed instructions, and always keep within authority." For an agent who acts upon these lines, there should never be any question of liability, or possible fear of the respon- sibility falling upon his shoulders. When a principal appoints an agent, then all the acts of the agent, and responsibilities incurred are for account of the principal as though he had acted personally, but only when he has given his agent the power to act in such manner. Should the agent exceed his authority and cany out an action which is outside the scope of his agency then the principal may refuse to accept responsibility. It should be observed, however, that the principal cannot impose secret limitations on the power of the agent; any limitations must be communicated to the other party. While the agent must act upon his instructions, he has implied powers given him to do everything necessary for the execution of any expressed authority he may have received. If the agent is appointed for the purpose of carrying out a certain duty, and receives authority to do so, but before he is able to proceed has to carry out other acts, then his authority is implied for such acts, it being under- stood that he could not have proceeded with his agency until such matters were attended to. A special point here which may be stressed is that whilst an agent receives authority to fix a charter-party, he has no authority to alter the charter-party in any manner after it has been signed, even if he sees that such an alteration is in his principal's interest. Having carried out his duty his responsibility ceases immediately. There is also no authority given to an agent to delegate his duty to another person to act for him. Having been selected as the agent of the principal, then he must carry out such agency himself, and he has no powers of delegation unless express or implied authority to delegate has been given to him by the principal, or unless it is permissible by custom of trade, or unless the nature of the business requires delegation.